Railway signaling



March 22, 1938.

c. H. LAY 2,112,104

RAILWAY SIGNALING Filed Dec. 1, 1936 3 Sheets-Sheet 1 INVENTOR Chame .Lay.

.1115 ATTORNEY March 22, 1938. c LAY 2,112,104

RAILWAY SIGNALING Filed Dec. 1, 1936 5 Sheets-Sheet 2 Fly. 15;

INVENTOR Clzarle Lay.

[1115' ATTORN EY March 22, 1938. c. H. LAY

RAILWAY SIGNALING 3 sheets-sheet 3 Filed Dec. 1, 1936 v INVENTOR CbaPl J'ZKLa ATTORNEY Patented Mar. 22, 1938 2,ll,l

ATENT RAILWAY SIGNALING Charles H. Lay, Swissvale, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application December 1, 1936, Serial No. 113,669 21 Claims. (01. 246- 38) My invention relates to railway signaling, and particularly to signaling involving wayside signals located along a trackway for governing the passage of trains.

A feature of my invention is the provision of novel and improved apparatus for establishing a' distinctive control for each of four track sections in the rear of an occupied section without the use'of line control wires. Each distinctive control is effective to cause a corresponding aspect of the wayside signals, whereby there is produced a four-block, five-indication system of signaling.

The present application is somewhat similar to a copending application Serial No. 692,155, filed October 4, 1933, by Howard A. Thompson, for Railway trafiic controlling apparatus, and said Thompson application contains claims which read on the present case.

I will describe two forms of apparatus embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawings, Figs. 1A, 1B, and 1C are diagrammatic views which, when placed end to end in the order named, illustrate one form of apparatus embodying my invention. Fig. 2 is a diagrammatic view illustrating a modification of a portion of the apparatus shown in Fig. 1A, and also embodying my invention.

Similar reference characters refer ,to similar parts in each of the several views.

Referring first to Figs. 1A, 1B, and 10, the reference characters l and 2 designate the trafiic rails of a stretch of railway track along which traffic normally moves in the direction indicated by the arrows. These rails are divided by the usual insulated joints 3 into a plurality of track sections V- W, W--X, X Y, Y-Z, etc.

Each track section is provided with a signal designated by a suitable distinguishing reference character and comprising an upper indication unit U and a lower indication unit L. As here shown, each unit U and L includes a stop lamp R capable of displaying a red light, a'caution lamp Y capable of displaying a yellow light, and a proceed lamp G capable of displaying a green light.

Each track section is provided with a track circuit including a battery 2- for'supplying energy to the rails at one end of the section and a polarized track relay, designated by the reference character 'I'. with a prefix the same as the reference character of the associated signal, connected directly across the track rails at the other end of the section.

Each track section is provided with a home relay, a distant relay, and an auxiliary relay designated by the reference characters H, D, and A, respectively, each with a prefix the same as the reference character of the associated signal.

Aswill be explained more in detail hereinafter, the relays H are controlled by the associated relay T, the relays A are controlled by the associated relays H and T, and the relays D are controlled by the associated relays A and T. The signals are controlled by the associated relays H, D, and T.

Each track section is provided with a pole changing relay and a code transmitting relay designated by the reference characters PC and F, respectively, each with a prefix the same as the reference character of the associated signal. As will be explained'more in detail hereinafter, the relays PC and F control the energy supplied torthe rails of the section next in rear. That is, current in the normal direction or in the reverse direction is supplied to the track circuit in the rear according as the relay F is energized or deenergized, respectively, and such current is constant or periodical according as the relay F is steadily energized or periodically energized, respectively.

The manner in which the signals are controlled will best be understood by tracing the circuits and explaining the operation of the apparatus simultaneously.

A train designated by the reference character K is shown in the section immediately to the right of location Z. The shunt of the wheels and axles of train K will deenergize the track relay .ST in the usualimanner so that all relays will be deenergized except code transmitting relay 9F.

Relay .lI-Ibeing deenergized, lamp R of the upper unit U of signal 9 is energized by a circuit which passes from terminal B of a suitable source of current over back point of contact it of relay .9H, and lamp R of that unit to terminal C of the same source of current and lamp R of the lower'unit L of signal 9 is energized over a. circuit which passes from terminal B over back point of contact R2 of relay 9H, and lamp R of that unit to terminal C, so that signal 9 is displaying a red light above a red light to indicate st p- The circuit for relay 9F may be traced from. terminal B over back point of contact it of relay 9H, back point of contact 14 of relay 9P0, and relay 9F to terminal C.

The connection of battery l at signal 9 to the track rails of the section YZ next in the rear of the section occupied by the train K will be over the back points of contacts l5 and E5 of relay SPC and front points of contacts ii and i8 of relay 9F, so that track relay 3T is energized in the reverse direction by constant current. Consequently, at the location Y, home relay 3H ,is energized over front point of contact is of relay 8T.

Lamp Y of the upper unit U of signal 8 is energized over a circuit which passes from terminal B through front point of contact 20 of relay 8H, back point of contact H of relay 8D, and lamp Y of that unit to terminal C, and lamp R of lower unit L of signal 8 is energized over a circuit which passes from terminal B through front point of contact 22 of relay 8H, reverse polar contact 2224 of relay 8T, back point of contact 5 of relay 8D, and lamp R. of that unit to terminal C, so that signal 8 is displaying a yellow light above a red light to indicate approach next signal prepared to stop.

Considering next the condition of the track circuit for the section XY which is the second section in rear of the section occupied by the train, the track circuit for the section XY is supplied with constant current of normal polarity because the front points of contacts 26 and 21 of relay 8PC and the front points of contacts 23 and 29 of relay 8F are all closed. The circuit for relay 8PC may be traced from terminal B through front point of contact 30 of relay 8H, back point of contact 3| of relay 8D, reverse polar contact 32-33 of relay BT, and relay SP0 to terminal C. The circuit for relay 8]? may be traced from terminal B over the same path as just traced for relay 81C up to and including reverse polar contact 3233 and thence through back point of contact 34 of relay 8D, front point of contact 35 of relay BPC, and relay 8F to terminal C. Consequently, relay IT is energized constantly in the normal direction and relay 1H also is energized over front point of contact 36 of relay 1T.

Current flows, therefore, from terminal B at location K through front point of contact 31 of relay EH, back point of contact 38 of relay ID, and lamp Y of the upper unit U of signal I to terminal C, so that lamp Y of that unit is illuminated. At the same time, current flows from the terminal B through front point of contact 39 of relay 1H, normal polar contact 40-41 of relay 1T, back point of contact 42 of relay ID, and lamp Y of the lower unit L of signal I to terminal C, so that lamp Y of that unit is illuminated. The aspect of signal i is, therefore, a yellow light above a yellow light to indicate proceed at not exceeding intermediate speed.

I shall next consider the condition of the track circuit for the section WX, the third section to the rear of the section occupied by the train K. The track relay GT is periodically energized in the reverse direction because the back points of contacts 43 and M of relay 'IPC are closed and the front points of contacts 45 and 46 of relay 1F are periodically closed. The circuit for relay 1F may be traced from terminal B through front point of contact 47 of relay II-I, back point of contact 38 of relay 7D, normal polar contact til-59 of relay "IT, back point of contact 5| of relay TPC, back contact 52 of relay 1F, and relay 1F to terminal C. Since the circuit for relay IF includes its own back contact 52, it will be readily apparent that this relay is being alternately energized and deenergized to cause the current supplied to the rails of section WX to be periodically interrupted.

Relay 6T being periodically energized, it follows that both relays 6H and 6D are also energized. That is, when the front point of contact 53 of relay 5T is closed, relay 6H is energized and when the back point of contact 53 is closed, relay 5A is energized over front contact 54 of relay 6H. When the front point of contact 53 of relay 6T again becomes close-d, relay 6D is energized over front contact 55 of relay 6A. Relays H,

A, and D are provided with a slow release characteristic so that the relays will maintain their front contacts closed during the open circuit periods. Since relay 6D can be energized only if both relay 6A and ST are picked up and relay BA can be energized only if relay GT is released and relay 6H is picked up, it follows that relay 6D can be energized only if relay ST is being periodically energized. The relays A are provided so that the associated relay D cannot become picked up upon a single release of the associated relay T. For example, if relay 8T should become released due to section Y-Z becoming occupied, relay 8D cannot become picked up to cause the momentary display of a less restrictive indication because relay 8D can be energized only if the front point of relay 8T is closed.

At signal 6, current flows from terminal B through frcnt point of contact 56 of relay 6H, reverse polar contact 5'l58 of relay GT, front point of contact 59 of relay 5D, and lamp Y of the upper unit U of signal 5 to terminal C, so that lamp Y of that unit is illuminated. Current also flows from the terminal B through front point of contact til of relay 5H, front point of contact SI of relay 6D, and lamp G of the lower unit L of signal 5 to terminal C, so that lamp G of that unit is illuminated. It follows that the aspect of the signal 6 is a yellow light above a green light to indicate, to a train approaching the location W, proceed at not exceeding medium speed.

Considering next the condition of the track circuit for the section VW, the fourth section to the rear of the section occupied by the train K, the track relay ET is periodically energized in the normal direction because front points of contacts 62 and 53 of relay GPC are closed and the front points of contacts 54 and 65 of relay 6F are periodically closed. The circuit for relay 6PC may be traced from terminal B through front points of contacts 65 and 61 of relays 6H and 6D, respectively, and relay EPC to terminal C. The circuit for relay 6F may be traced over the same path as just traced including front contact 61 and thence over front point of contact 68 of relay 6D, front point of contact 69 of relay GPC, back contact 76 of relay 6F, and relay GP to terminal C.

Relay 5T being periodically picked up and released, it follows that relays 5H and 5D are both picked up over circuits similar to those traced for relays 6H and 5D at location W.

Current is, therefore, flowing from terminal B through the front point of contact ll of relay 5H, normal polar contact 72-43 of relay 5T, front point of contact '54 of relay 5D, and lamp G of the upper unit U of signal 5 to terminal C, so that lamp G of that unit is illuminated. Current is also flowing from terminal 13 through front point of contact 15 of relay 5H, front point of contact 16 of relay 5D, and lamp G- of the lower unit L to terminal C, so that lamp G of that unit is illuminated. The aspect of the signal 5 is, therefore, a green light above a green light to indicate proceed at normal speed.

From the foregoing description, it is evident that a distinctive control condition is provided for each of the four successive track sections to the rear of an occupied section. These control conditions may be summed up as follows: The track circuit for the section occupied is shunted in the usual manner to open the track relay of that section. The first section to the rear of the occupied section has its track cirdium and proceed aspects can be displayed cuit supplied with constant current of normal polarity. The third section has its track circuit supplied with periodically interrupted current of reverse polarity and the fourth section has its track circuit supplied with periodically inter-, rupted current'of normal polarity. From these different control conditions, five different signal aspects are obtained, namely, a red light above a red light at the first signal to the rear of a train to indicate stop, a yellow light above a red light at the second signal to the rear of a train to indicate prepare to stop at the next signal, a yellow light above a yellow light at the third signal to the rear'of a train to indicate proceed at not exceeding intermediate speed, a yellow light above a green light at the fourth signal to indicate proceed at not exceeding medium speed, and a green light above a green light at the fifth signal to the rear of a train to indicate proceed at normal speed. I shall term these aspects, stop, approach, approach intermediate, approach medium, and proceed,

only if the track relays are periodically energized. Therefore, if a track relay remains picked up constantly when it should be periodically picked up, the associated signal will be caused to display one of the more restrictive aspects.

It should also be noted that, whenever the code transmitting relays F are released, the rails of the section next in rear are shunted by a connection 'll as well as disconnected from track battery 4. This shunt path insures more positive response of the relays T in that any foreign current present in the rails will be shunted away from the track relay.

Although a specific combination of lights is here set forth for the different signal aspects, it will be understood that my invention is not limited to this one arrangement and other combinations of lights may be obtained should some other arrangement of aspects seem desirable.

Referring now to Fig. 2, I have shown herein a signal and associated apparatus which when connected in a system will provide four-block, five-indication signaling capable of displaying the same indications as those described for the system shown in Figs. 1A,1B, and 1C. The principal difference in the apparatus shown in Fig. 2 from the apparatus shown in Figs. 1A, 1B, and 1C is in the manner in which the periodical and constant current control the signal aspects. That is, in Fig. 2, the two least restrictive aspects are displayed when the relay T is supplied with constant energy and the two most restrictive aspects are provided when the relay T is supplied with periodic energy, which arrangement is just the opposite of that described for the apparatus shown in Figs. 1A, 1B and 1C.

The relays E and J are controlled by the track relay T in such a manner that the relay J becomes energized whenever the relay T is picked up and the relay E becomes energized whenever the relay T is released provided the relay J is picked up. That is, when front point of contact 8B of relay T is closed, relay J becomes picked up and, when back point of contact 80 is closed, relay E becomes picked up over front contact 8! of relay J. Relay J is somewhat slow in releasing in order to provide a pickup path for relay E when rela'y T is released. In other words, the relays E and J become alternately picked up according as relay T becomes picked up and released, respectively.

The home and distant relays H and D are controlled by the relays E and J in such a manner that the relay H becomes picked up whenever either relay E or J is picked up and relay D becomes picked up whenever relay J is picked up provided relay E is released. That is, the relay H becomes energized whenever front point of contact 82 of relay E is closed or whenever front contact 83 of relay J is closed, and relay D becomes energized only when back point of contact 82 of relay J is closed provided front contact 84 of relay J is closed. Because either relay J or relay E will be picked up whenever relay T is energized, either periodically or constantly, it follows that relay H will be picked up whenever relay T is supplied with constant energy or periodic energy. Relay D, however, can be picked up only if relay E is released and relay J is picked up and, consequently, only when relay T is constantly energized. Although, there may be periods of comparatively short duration when relay D may be energized while relays E and J are alternately picking up and releasing, the relay D is provided with a slow pickup characteristic so that this relay will not become picked up upon receiving such momentary energizations but will only become picked up if relay El remains released and relay J remains picked up for a predetermined interval of time.

The relays H, D, and T control the signal lamps and the relay PC controls the track circuit next in rear in a manner exactly similar to that described for the system shown in Figs. 1A, 1B, and 1C, and it is thought, therefore, that further detailed description of this apparatus is unnecessary. The relay F, however, is controlled in a somewhat different manner from that described for the system illustrated in Figs. 1A, 1B, and 1C.

The relay'F is provided with two stick circuits each including its own front contact and with an operating circuit including its own back contact. That is, whenever both relays H and D are energimd, the first stick circit is effective to maintain relay F in its picked up condition provided relay PC is energized, and whenever relay H is energized and relay D is deenergized, the second stick circuit is effective to maintain relay F in its picked up condition provided relay T is energized in the normal direction and relay PC is deenergized. The first circuit may be traced from terminal B through front point of contact 85 of relay H, front point of contact 86 of relay D, front point of contact 89 of relay PC, front point of contact 90 of relay F, and relay F to terminal C. The second stick circuit may be traced from terminal B through front point of contact 85 of relay H, back point of contact 86 of relay D, normal polar contact 9|92 of relay T, back point of contact 89 of relay PC, front point of contact 96 of relay F, and relay F to terminal C. Whenever both of the stick circuits are opened, that is, whenever relay T is deenergized or is periodically energized in the reverse direction, the relay F becomes periodically energized over the back point of its own contact 90.

It will be readily apparent how the current supplied to the rails of the rear section from battery 4 will be of normal or reverse polarity according as the front or back points, respectively, of contacts 93 and 94 of relay PC are closed, and how such current will be constant or periodical according as the front points of contacts 95 and 96 of relay F are constantly closed or periodically closed, respectively.

Although I have herein shown and described only two forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a section of railway track, a polarized relay for said section, means effective when the section is unoccupied for supplying said relay with periodically interrupted current of one polarity or with periodically interrupted current of the other polarity or with constant current of said one polarity or with constant current of said other polarity in accordance with trafiic conditions in advance of said section, a signal for the section capable of displaying four distinctive proceed indications, and means controlled exclusively by said relay and selectively responsive to said four forms of current for selectively controlling said signal.

2. In combination, a section of railway track, a polarized relay for said section, means effective when the section is unoccupied for supplying said relay with periodically interrupted current of one polarity or with periodically interrupted current of the other polarity or with constant current of said one polarity or with constant current of said other polarity, a home relay which becomes energized whenever said polarized relay is energized either by periodic current or constant current, a distant relay which becomes energized only when said polarized relay is energized by periodic current, a signal for said section capable of displaying four distinctive proceed indications, and means controlled exclusively by said three relays for selectively controlling said signal.

3. In combination, a section of railway track, a polarized relay for said section, means effective when the section is unoccupied for supplying said polarized relay with periodically interrupted current of one polarity or with periodically interrupted current of the other polarity or with constant current of said one polarity or with constant current of said other polarity, a home relay which becomes energized whenever said polarized relay is energized either by constant current or periodic current, a distant relay which becomes energized only when said polarized relay is energized by constant current, a signal for said section capable of displaying four distinctive proceed indications, and means controlled exclusively by said three relaysfor selectively controlling said signal.

4. In combination, a section of railway track, a polarized relay which becomes released whenever said section is occupied, means effective when said section is unoccupied for supplying said relay with periodically interrupted current of one polarity or with periodically interrupted current of the other polarity or with constant current of said one polarity or with constant current of said other polarity, a signal for said section capable of displaying a stop and four distinctive proceed indications, and means controlled exclusively by said polarized relay and selectively responsive to its released condition or its four energized conditions for selectively controlling said signal.

5. In combination, a section of railway track, a polarized relay for said section, means effective when said section is unoccupied for supplying the rails of said section with periodically interrupted current of normal polarity or with periodically interrupted current of reverse polarity or with constant current of said normal polarity or with constant current of said reverse polarity in accordance with traflic conditions in advance of said section, a home relay which becomes energized whenever said polarized relay is energized either periodically or constantly, a distant relay which becomes energized only when said polarized relay is energized periodically, a signal for said section including a first unit and a second unit each comprising a proceed and a stop as well as a caution lamp, a circuit for the proceed lamp of said first unit including a front contact of said home relay and a front contact of said distant relay as well as a normal polar contact of said polarized relay, a circuit for the caution lamp of said first unit including a front contact of said home relay and a front contact of said distant relay as well as a reverse polar contact of said polarized relay, another circuit for said caution lamp including a front contact of said home relay and a back contact of said distant relay, a circuit for the stop lamp of said first unit including a back contact of said home relay, a circuit for the proceed lamp of said second unit including a front contact of said home relay and a front contact of said distant relay, a circuit for the caution lamp of said second unit including a front contact of said home relay and a back contact of said distant relay as Well as a normal polar contact of said polarized relay, a circuit for the stop lamp of said second unit including a back contact of said home relay, and another circuit for said stop lamp including a front contact of said home relay and a back contact of said distant relay as well as a reverse polar contact of said polarized relay.

6. In combination, a section of railway track, a polarized relay for said section, means effective when said section is unoccupied for supplying said relay with periodically interrupted current of one polarity or with periodically interrupted current of the other polarity or with constant current of said one polarity or with constant current of said other polarity, a signal for said section, and means controlled exclusively by said polarized relay for causing said signal to display one indication when said relay is energized periodically by current of one polarity or for causing said signal to display a less restrictive ind.- cation when said relay is energized periodically by current of the other polarity or for causing said signal to display a still less restrictive indication when said relay is energized constantly by current of said one polarity or for causing said signal todisplay a still further less restrictive indication when said relay is energized constantly by current of said other polarity.

7. In combination, a section of railway track, means governed in accordance with trafiic con ditions in advance of said section for supplying the rails of the section with periodically interrupted current of one polarity or with periodically interrupted current of the other polarity or with constant current of said one polarity or with constant current of said other polarity, a polarized track relay connected across the rails of said section, a five-aspect signal for said section, and

means governed in accordance with traffic con-' ditions in advance of said section for supplying the rails of the section with constant current of one polarity or with constant current of the other polarity or with periodically interrupted current of one polarity or with periodically interrupted current of the other polarity, a polarized track relay connected across the rails of said section, a signal for said section capable of displaying four distinctive proceed indications, and means controlled exclusively by said track relay and selectively responsive to said four forms of current for selectively controlling said signal.

9. In combination, a section of railwaytrack, a polarized relay for said section, means effective when said section is unoccupied for supplying said relay with periodically interrupted current of normal polarity or with periodically interrupted current of reverse polarity or with constant current of said normal polarity or with constant current of said reverse polarity in accordance with traffic conditions in advance of said section, a home relay and a distant relay, means controlled exclusively by said polarized relay for selectively governing said home and distant relays'according' as said polarized relay is supplied with constant current or periodically interrupted current, a signal for said section including a first unit and a second unit each comprising a proceed and a stop as well as a caution lamp, and means governed by said three re lays for selectively governing said lamps to provide four distinctive proceed indications.

10. In combination, a section of railway track, a polarized relay for said section, means'eifective when said section is unoccupied for supplying said relay with periodically interrupted current of one polarity or with periodically interrupted current of the other polarity or with constant current of said one polarity or with constant current of said other polarity in accordance with trafiic conditions in advance of said section, a signal for said section, and means controlled exclusively by said relay for causing said signal to display one indication when said relay is energized constantly by current of one polarity or for causing said signal to display a less restrictive indication when said relay is energized constantly by current of the other polarity or for causing said signal to display a still less restrictive indication when said relay is energized periodically by current of said one polarity or for causing said signal to display a still further less restrictive indication when said relay is energized periodically by current of said other polarity.

11. In combination, a section of railway track, a polarized relay for said section, means efiective when the section is unoccupied for energizing said relay with. constant current in one direction or with constant current in the ot er direction or with periodically interrupted current in said one direction or with periodically interrupted current in said other direction in accordance with traffic conditions in advance of said section, a home relay which'becomes picked up whenever said polarized relay is'energized either by constant current or periodic current, an auxiliary relay which be comes picked up whenever said polarized relay is released provided said home relay is picked up, a distant relay which becomes picked up whenever said polarized relay is picked up provided said auxiliary relay also is picked up, a signal for said section capable of displaying four distinctive proceed aspects, and means governed by said polarized relay as well as by said home and distant relays for selectively governing said signal.

12. In combination, a section of railway track, a polarized relay for said section, means effective when the section is unoccupied for energizing said relay with constant current in one direction or with constant current in the other direction or with periodically interrupted current in said one direction or with periodically interrupted current in said other direction in accordance with trafiic conditions in advance of said section, a home relay and a distant relay as well as an auxiliary relay each having aslow release characteristic, a circuit for said home relay including a front contact of said polarized relay, a circuit for said auxiliary relay including a back contact of said polarized relay and a front contact of said home relay, a circuit for said distant relay including a front contact ofsaid polarized relay and a front contact of said auxiliary relay, and a signal for said section controlled by said polarized relay as well as by said home and distant relays.

13. In combination, a forward and a rear section of railway track, a polarized relay for the forward section which becomes deenergized when that section is occupied, means effective when the forward section is unoccupied for energizing said polarized relay with constant energy in one direction or with constant energy in the other direction or with periodically interrupted energy in said one direction or with periodically interrupted energy in said other direction in accordance with trafiic conditions in advance of said forward section, a polarized relay for the rear section, and means governed exclusively by said polarized relay for the forward-section for se lectively governing said polarized relay for the rear section when such rear section is unoccupied.

14. In combination, a forward and a rear section of railway track, a polarized relay for the forward section which becomes deenergized when that section is occupied, means effective when the forward section is unoccupied for energizing said polarized relay with constant energy in one direction or with constant energy in the other direction or with periodically interrupted energy in said one direction or with periodically interrupted energy in said other direction in accord ance with trafiic conditions in advance of said forward section, a polarized relay for the rear section, and means governed exclusively by said polarized relay for the forward section for selec- 'tivel'y supplying said polarized relay for the rear section with four diiferent characters of current respectively when said rear section is unoccupied.

15. In combination, a forward and a rear section of railway track, a polarized relay for the forward section which becomes deenergized when that section is occupied, means effective when the forward section is unoccupied for energizing said polarized relay with constant energy in one direction or with constant energy in the other direction or with periodically interrupted energy in said one direction or with periodically interrupted energy in said other direction in accordance with traffic conditions in advance of said forward section, a polarized relay for the rear section, and means including a pole changing relay and a coding relay governed exclusively by p the polarized relay for the forward section for selectively governing said polarized relay for the rear section.

16. In combination, a forward and a rear section of railway track, a polarized relay for the forward section which becomes deenergized when that section is occupied, means effective when the forward section is unoccupied for energizing said polarized relay with constant energy in one direction or with constant energy in the other direction or with periodically interrupted energy In said one direction or with periodically interrupted energy in said other direction in accordance with trafiic conditions in advance of said forward section, and means governed exclusively by said polarized relay for selectively governing the supply of current to the rear section.

1'7. In combination, a forward and a rear section of railway track, a polarized relay for the forward section which becomes deenergized when that section is occupied, means effective when the forward section is unoccupied for energizing said polarized relay with constant energy in one direction or with constant energy in the other direction or with periodically interrupted energy in said one direction or with periodically interrupted energy in said other direction in accordance with traffic conditions in advance of said forward section, a home relay which becomes energized whenever said polarized relay is energized constantly or periodically, a distant relay which becomes energized only when said polarized relay is energized periodically, a pole changing relay and a code transmitting relay for governing the supply of current to the rear section, a circuit for said pole changing relay including a front contact of said home relay and a back contact of said distant relay as well as a reverse polar contact of said polarized relay, another circuit for said pole changing relay including a front contact of said home relay and a front contact of said distant relay, a circuit for said code transmitting relay including a back contact of said home relay and a back contact of said pole changing relay, another circuit for said code transmitting relay including a front contact of said home relay and a back contact of said distant relay as well as a reverse polar contact of said polarized relay and a front contact of said pole changing relay, still another circuit for said code transmitting relay including a front contact of said home relay and a back contact of said distant relay as well as a normal polar contact of said polarized relay and a back contact of said pole changing relay in addition to a back contact of said code transmitting relay, and still a different circuit for said code transmitting relay including its own back contact and a front contact of said home relay as well as a front contact of said distant relay and a front contact of Said pole changing relay.

18. A railway signal system including a plurality of consecutive track sections, a polarized relay for each section each connected across the rails of the associated section, a five-aspect signal for each section, means controlled exclusively by the track relay for each section for selectively governing the associated signal, and means for supplying the rails of each section with constant current of one polarity or the other or with periodically interrupted current of one polarity or the other in accordance with traffic conditions in advance of the associated section.

19. In combination, a section of railway track, a polarized relay for said section which becomes released when said section is occupied, means effective when said section is unoccupied for supplying said relay with periodically interrupted current of one polarity or with periodically interrupted current of the other polarity or with constant current of said one polarity or with constant current of said other polarity in accordance with traffic conditions in advance of said section, a first and a second auxiliary relay, a circuit for said first auxiliary relay including a front contact of said second auxiliary relay and a back contact of said polarized relay, a circuit for said second auxiliary relay including a front contact of said polarized relay, a home relay and a distant relay, means for energizing said home relay when either auxiliary relay is picked up, means for energizing said distant relay when said second auxiliary relay is picked up provided said first auxiliary relay is released, and a signal for said section governed by said polarized relay and said home relay as well as said distant relay.

20. In combination, a forward and a rear section of railway track, a polarized relay which becomes deenergized when the forward section is occupied, means effective when the forward secion is unoccupied for energizing said polarized 7 relay with periodically interrupted current in one direction or with periodically interrupted current in the other direction or with constant current in said one direction or with constant current in said other direction in accordance with traffic conditions in advance of said forward section, a home relay which becomes picked up whenever said polarized relay is supplied with constant current or periodical current, a distant relay which becomes picked up only when said polarized relay is supplied with constant current, a pole changing relay and a code transmitting relay for governing the supply of current to the rear section, a circuit for said pole changing relay including a front contact of said home relay and a back contact of said distant relay as well as a reverse polar contact of said polarized relay, another circuit for said pole changing relay including a front contact of said home relay and a front contact of said distant relay, a circuit for said code transmitting relay including its own back contact, another circuit for said code transmitting relay including its own front contact and a back contact of said pole changing relay as well as a normal polar contact of said polarized relay and a back contact of said distant relay in addition to a front contact of said home relay, and still a different circuit for said code transmitting relay including its own front contact and a front contact of said pole changing relay as well as a front contact of .both said home relay and said distant relay.

21. In combination, a plurality of successive sections of railway track, means for supplying the rails of each section with constant current in one direction or with constant current in the other direction or with periodically interrupted current in said one direction or with periodically interrupted current in said other direction in accordance with traffic conditions in advance of the associated section, a polarized relay for each section connected across the rails of the associated section, other means for each section governed exclusively by the associated polarized relay and selectively responsive according to the character of the current received by such relay, and trafiic gov'erning means for each section governed by the associated other means.

CHARLES H. LAY. 

